svn commit: r208165 - in head/sys: kern mips/conf mips/include
mips/mips mips/rmi mips/rmi/dev/xlr
c.jayachandran at gmail.com
Mon Aug 9 14:26:53 UTC 2010
On Mon, Aug 9, 2010 at 5:35 PM, Attilio Rao <attilio at freebsd.org> wrote:
> 2010/8/9 Jayachandran C. <c.jayachandran at gmail.com>:
>> On Mon, Aug 9, 2010 at 5:31 AM, Attilio Rao <attilio at freebsd.org> wrote:
>>> 2010/5/16 Randall Stewart <rrs at freebsd.org>:
>>>> Author: rrs
>>>> Date: Sun May 16 19:43:48 2010
>>>> New Revision: 208165
>>>> URL: http://svn.freebsd.org/changeset/base/208165
>>>> This pushes all of JC's patches that I have in place. I
>>>> am now able to run 32 cores ok.. but I still will hang
>>>> on buildworld with a NFS problem. I suspect I am missing
>>>> a patch for the netlogic rge driver.
>>>> JC check and see if I am missing anything except your
>>>> core-mask changes
>>>> Modified: head/sys/kern/subr_smp.c
>>>> --- head/sys/kern/subr_smp.c Sun May 16 19:25:56 2010 (r208164)
>>>> +++ head/sys/kern/subr_smp.c Sun May 16 19:43:48 2010 (r208165)
>>>> @@ -503,7 +503,10 @@ smp_topo_none(void)
>>>> top = &group;
>>>> top->cg_parent = NULL;
>>>> top->cg_child = NULL;
>>>> - top->cg_mask = (1 << mp_ncpus) - 1;
>>>> + if (mp_ncpus == sizeof(top->cg_mask) * 8)
>>>> + top->cg_mask = -1;
>>>> + else
>>>> + top->cg_mask = (1 << mp_ncpus) - 1;
>>>> top->cg_count = mp_ncpus;
>>>> top->cg_children = 0;
>>>> top->cg_level = CG_SHARE_NONE;
>>> ... and this is why I particulary hate big commits with complete lack
>>> of technical details.
>>> This particulary chunk was supposed to fix a nasty and completely MI
>>> bug that some users have already met (kern/148698). The complete lack
>>> of details didn't help in identify the issue neither that it was a
>>> valuable fix.
>>> The fix is, however, improper (there is no clear relationship between
>>> the multiplication and why that happens) thus I would rather use what
>>> Joe has reported in the PR.
>> I was not aware of the PR when I sent this changes to rrs@, and this
>> went as a part of MIPS SMP support for XLR which has 32 CPUs
>> But I'm not sure that the current change is correct, cg_mask is of
>> type cpumask_t and I don't think it is guaranteed to be 32 bit (as it
>> is a machine dependent type).
> Actually the 32 bits limit is well aware and acknowledged in cpumask_t.
> While it is true that it should be an 'opaque' type, in reality it is
> not. The maximum limit of 32 CPUs is a reality due to cpumask_t on all
> our architectures.
> That is why we are going to use cpuset_t for dealing with CPUs numbers
> (which is really opaque, at same extent, and is not bound to any
In my opinion, your changes added another pitfall for the person who
tries to make the cpumask_t 64 bit to support more cpus, which really
could have been avoided.
But if cpumask_t is going to be changed to cpuset_t soon, I guess we
are fine :)
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